The invention relates to a gearbox, particularly for a motor vehicle, with multiple shafts such as a first and a second gear input shaft and a gear output shaft as well as a multitude of gear pairs between the gear output shaft and the gear input shafts, consisting of an idler that is arranged around one of the shafts, respectively, and connected with it in a stationary manner, and a fixed wheel that is arranged in a stationary manner on a corresponding shaft so as to comb with the idler for the purpose of forming gears with different gear ratios between the gear input shaft and one of the gear output shafts.
Such gears are basically known particularly in connection with internal combustion engines and the separation of the gear input shafts through a clutch of the crankshaft and represent the state of the art for the task of further developing and automating these gearboxes. One aspect of the task is to manufacture this gearbox in the automatic version in a cost effective manner, another aspect of the task is the economical operation of a drive branch with such a gearbox. Furthermore, a partial aspect of the task consists of creating a method for the ecological and comfortable operation of a motor vehicle with a gear box pursuant to the disclosed application documents.
This task is resolved with a gearbox, particularly for motor vehicles, with a multitude of shafts such as a first and a second gear input shaft and an output shaft, which in a beneficial version can also be formed by two shaft branches that can be united later one, for example, with a differential or toothed wheel work, with this gearbox being equipped with at least the following features:
a) a multitude of gear pairs is arranged between the gear output shaft and the gear input shafts, consisting of an idler that is arranged around one of the shafts, respectively, and connected with it in a stationary manner, and a fixed wheel that is arranged in a stationary manner on a corresponding shaft so as to comb with the idler for the purpose of forming gears with different gear ratios between the gear input shaft and one of the gear output shafts;
b) at least one gear input shaft can be driven at least in part through a drive unit with a drive shaft;
c) at least one gear input shaft can be connected with a first electric unit;
d) the gear output shaft can be connected with at least one driving wheel;
e) at least one gear can be actuated automatically with an actuator.
For this embodiment, the idler and fixed wheels that are formed by the gear pairs can be arranged on the gear input shafts and/or the gear output shaft, wherein it may be beneficial to arrange the idlers on the gear input shafts, respectively. Furthermore, it may be beneficial for other embodiments to arrange the idlers on the gear output shaft, particularly in transmissions where the appropriate fixed wheels can be arranged rationally on the gear input shafts because their diameter can be designed so small that they can be easily manufactured in a firmly connected version or single-piece version through forging, milling, stamping processes, through hot flow processes such as lateral extrusion or similar processes. The drive unit can be formed by an internal combustion engine, for example, a piston engine with crankshaft, with appropriate devices being provided for dampening torsional oscillation, axial and/or wobble oscillation between the internal combustion engine and the transmission. Furthermore, the drive unit can be formed by a second electric unit, wherein the first as well as the second electric unit, which can also be operated in a polyphase manner as an electric engine and/or generator based on the synchronous, asynchronous and/or reluctance principle, can drive one gear input shaft, respectively, and can have roughly the same dimensions. Particularly in connection with the usage of an internal combustion engine as the drive unit, it is particularly beneficial to design its drive shaft so that it can be coupled with the gear input shafts, wherein at least one gear input shaft, preferably both, can be coupled with the drive shaft. One embodiment in accordance with the invention provides for a design where the clutches are friction clutches, preferably dry friction clutches, in the form of a double clutch, with this being possibly arranged in the clutch housing of the gearbox, i.e. axially between the drive unit and the transmission. For this version, the previously mentioned dampening devices can be integrated in the double clutch, furthermore a flywheel that may be provided can hold the clutches, wherein the various clutch components can be fastened to the flywheel as modules and the flywheel can be a divided flywheel with two-mass effect.
Based on one inventive idea, the drive unit can furthermore be formed by an internal combustion engine with a crankshaft that can be connected with one gear input shaft, respectively, through a double clutch. For this purpose, an electric unitxe2x80x94such as the one described above as the first electric unitxe2x80x94can be connected additionally with at least one gear input shaft in such a manner that it can be uncoupled. It can also prove particularly beneficial to arrange the electric unit so as to allow it to be connected alternatively with both gear input shafts. This connection can be formed by a friction, shifting or magnetic clutch, which creates the connection from the electric unit to the gear input shaft by building up electro-magnetic fields, wherein the formation of the connection and/or the selection of this clutch can occur through an actuator of the electric, hydraulic and/or pneumatic as well as a combined procedure or in the case of a magnetic clutch through the appropriate selection of the electric currents through the device adjusting the magnetic effect, such as coils or similar devices. Of course, two clutches can also be beneficial for forming a connection between the gear input shafts and the electric unit that can be uncoupled, wherein one clutch, respectively, can connect the electric unit with one of the gear input shafts and two appropriate actuators can be used for this purpose.
Beneficial embodiments of the gearbox provide for the fact that the gear output shaft can be arranged basically coaxially to the drive shaft and/or that one of the gear input shafts is arranged basically coaxially to the drive shaft. It can prove particularly beneficial to arrange one gear input shaft as a hollow shaft around the other gear input shaft. In a beneficial version, the gear pairs that form the individual gears can be arranged alternating on the two gear input shafts in dependence of the gear ratios. This way it is possible to operate the vehicle through a gear input shaft, which is connected with the internal combustion engine through the appropriate clutch, and a gear with one gear ratio, while on the other gear input shaft the next gear ratio is engaged with an engaged clutch between the gear input shaft and the internal combustion engine. This way, for example, four, preferably six, separate forward speeds and one reverse speed can be incorporated in these transmissions, wherein those gears with an increasing gear ratio can be arranged on one gear input shaft and those gears with gear ratios in between the gear ratios of that on the first gear input shaft can be arranged on the other gear input shaft. The reverse gear can be arranged on either of the two gear input shafts. In an alternative to this embodiment, the motor vehicle can be operated purely electrically in reverse, wherein the electric unit is operated in the opposite rotational direction. The preferred starting gear with the smallest gear ratio can, for example, be arranged on the first one, the second gear with the next higher gear ratio on the second one, the third gear again on the first one and the fourth gear again on the second one etc. The electric unit can be connected with the gear input shaft that contains the gear with the smallest or the gear with the next smaller gear ratio. The individual gears are preferably formed through fixed wheels and idlers, which are arranged on one shaft, respectively, such as the gear input shaft and the gear output shaft, wherein for the purpose of activating the gear the appropriate idlers is connected with the shaft, for example, through a sliding sleeve. In a beneficial version, the idlers can be arranged on the gear input shafts, on the gear output shaft or depending on the requirement alternating on one of the gear input shafts and the gear output shaft or driven shaft. As known, the idlers can be placed on the appropriate shafts such as gear input shaft and/or gear output shaft in a synchronized manner with regard to a speed between the shafts carrying the two gear pairs, wherein this synchronization process can occur with conventional synchronizing devices or alternatively or additionally with the electric unit and wherein the electric unit can be used in a driving or braking manner in accordance with the required minimum of the differential speed between the two shafts for achieving a synchronizing speed. Furthermore, it may be particularly beneficial to accelerate the synchronization process by decelerating or accelerating the gear input shaft, by operating it at least in a slipping manner with the drive unit through the clutch, which is generally engaged when the torque is transferred through the other gear input shaft.
With regard to the arrangement of the electric unit on the gearbox it has proven particularly beneficial to arrange it on the end of the gear input shaft that is opposite the drive unit such as the internal combustion engine. Of course, it can also be beneficial to arrange the electric unit parallel to one of the gear input shafts, wherein an arrangement parallel to the axis through an active connection such as a belt, chain, toothed wheel connection or similar is selected and the electric unit can be arranged in the area of the double clutch or at axial height of the gear. When arranged on the side of the gear that is opposite the drive unit, a coaxial arrangement of the electric unit to the gear input shaft, with which the electric unit is connected, can be beneficial. Additionally, the electric unit can be arranged around the clutch, for example, around the double clutch of the double clutch gearbox, which offers the advantage that additional axial space is largely eliminated and that due to a larger diameter the electric unit can have a stronger, i.e. more powerful, design. With regard to an active connection of the electric unit to the double clutch gear, it may be beneficial to arrange the electric unit on the gear wheels that are arranged on one of the gear input shafts, next to the direct coupling to the gear input shaft. This way, the electric unit, when used as a motor or generator, can be adjusted to the speed-dependent efficiency maximum level of the electric unit by utilizing the various gear ratios on the gears that can be engaged on this gear input shaft. On the other hand, it has turned out that particularly during recuperation processes kinetic energy that can be converted into electric energy is recuperated with a long power branch, such as in the case of an active connection of the electric unit with the gear with the largest gear ratio, when recuperating in a gear with small gear ratio. In this case, kinetic energy is guided, for example, through three gear pairs so that a loss of efficiency must be tolerated. Based on the inventive idea it can prove particularly beneficial in such cases to actively connect the electric unit preferably on the gears and/or the gear wheels with a mean gear ratio, for example, in dependence on the selection of the gear input shaft preferably on gear II or gear IV and/or gear III.
Additionally, the electric unit can be arranged on the gear output shaft, wherein it is arranged in an articulating way around it and can be actively connected with the gear input shaft. This is particularly beneficial in so-called in-line gearboxes where the gear output shaft is arranged coaxially to the crankshaft. The electric unit can be positioned on the gear output shaft at the end of the gearbox that is opposite the crankshaft, and can thus be arranged optimally for spatial reasons. This can include an articulating arrangement around the gear output shaft so as to arrange the rotor around the gear output shaft and seat it in an articulating manner or to seat the rotor in an articulating manner in relation to the gear housing. In both cases, the stator must be firmly connected with the gear housing. As in the remaining embodiments, the electric unit can have an external or internal design, i.e. with a rotor that is arranged around the stator or within the stator. The electric unit can basically be a synchronous, asynchronous or reluctance type. The active connection between rotor and gear input shaft can occur through a belt design, a toothed wheel connection or similar, wherein it may be particularly beneficial to connect the electric unit with a gear wheel of a gear wheel pair of one gear, for example, a gear with high gear ratio, e.g. gear V. Beneficially, a gear is selected whose gear ratio is larger than the gear ratio of the direct speed (speed of the crankshaft is equal to the speed of the gear input shaft) so that an appropriate gear ratio of these two gears between the electric unit and the internal combustion engine exists, which allows the electric unit to be operated in generator mode at the speeds within efficiency and the internal combustion engine to be started by the electric unit with appropriate smaller speeds of the crankshaft and high speeds of the electric unit. Additionally, it may be beneficial to connect the rotor, for example, with the gear output shaft in a stationary manner through a shifting clutch to further spread the speed range of the electric unit.
At least one secondary unit can be connected with the electric unit from a drive point of view, and it may be particularly beneficial when in the case of an arrangement of the electric unit parallel to the axis of the gear input shaft the electric unit is integrated into the pulley plane of the secondary unit. The electric unit can perform a drive function in the conventional sense, wherein the electric unit beneficially can be uncoupled from the gear input shaft so that the secondary units can be operated by the electric unit independently from the speed of the gear input shaft, i.e. also independently from the speeds of the driving wheels and the speed of the drive shaft of the internal combustion engine. This offers the advantage that, if it is desired to operate the secondary units electrically independently from the drive unit, the separate supply of these secondary units with one electric unit, respectively, can be eliminated and an appropriate weight reduction can occur. Furthermore, a gear ratio can be provided between the electric unit and at least one secondary unit that can be adjusted variably, for example, through a variably adjustable gearbox (CVT) or through toothed wheel connections that can be actuated automatically or manually. It can also prove beneficial to uncouple the electric unit from at least one secondary unit through a so-called secondary unit clutch. Several secondary units that are arranged in one pulley plane can be separated from, connected with and/or have a gear ratio in relation to each other and/or to the electric unit, which can be accomplished with clutches, free-wheels and appropriate gearboxes for selecting variable and/or fixed gear ratios.
Based on another idea of the invention, the connection between the drive shaft and at least one of the gear input shafts can be either reduced or multiplied. This gear ratio process or pre-multiplication can occur beneficially through gear wheel steps, wherein already a graduation of the gear input shafts among each other can occur by subjecting one gear input shaft to a gear ratio, but not the other. Additionally, the advance gear ratio process of the r.p.m. range of the gear input shafts can be adjusted so as to operate the electric unit independently from the engaged gear at an optimized speed, i.e. a speed that has been adjusted for the electric unit with regard to its efficiency. Of course, the appropriate gear ratio process can also occur directly between the gear input shaft and the electric unit, particularly in the case of an arrangement of the gear input shaft parallel to the axis of the electric unit with an active connection between these components, such as belt operation, chain drive, gear wheel drive and similar arrangements.
Based on another idea of the invention, the drive branch consisting of the drive unit such as an internal combustion engine, the clutch device such as the double clutch and the gearbox such as the double clutch transmission is provided for automatic actuation, wherein at least one clutch and/or one gear can be engaged automatically in dependence on the driving situation. The design of the drive branch as fully automatic gearbox with two clutches that can be actuated fully automatically and the fully automatic actuation of all gears however is advantageous. This way, at least one gear or one clutch is actuated by an actuator, which can be an electric, hydraulic, pneumatic or combined actuator. In a beneficial embodiment such an actuator is provided for each gear, wherein it can prove particularly beneficial to engage two neighboring gears, respectively, that are arranged on one gear input shaft through shifting sleeves such as sliding sleeves that are engaged by an appropriate actuator, for example, a pair of gears consisting of a first gear and a neighboring gear on the gear input shaft can be engaged by an actuator. A pair of gears can be formed, for example, by the first and the third gear, wherein the shifting sleeve can override a possibly adjustable neutral position between activation of the first gear and activation of the second gear by forming a positive lock with the gear input shaft. It can be beneficial to combine an individual gear that cannot be combined with a pair of gears with the gear input shaft through connection with the electric unit so that with this sliding sleeve an actuator either engages this gear or connects the electric unit with the gear input shaft or activates optionally a neutral mode.
Based on another idea of the invention, gear ratio steps can be actuated through an actuator on the gear input shafts that are equipped with a synchronizing device on the last gear pair, for example, of the first gear input shaft that does not actively connect with the electric unit, wherein gear ratio steps are engaged by connecting an idler with the shaft that holds it through an end output element, which is part of an end output mechanism that is actuated by the end actuating mechanism, and wherein the shifting sequence of the gear ratio steps is not set in the end actuating mechanism. The end output element here is the element that is moved in order to set a gear ratio, i.e. the one that establishes the connection between two power transmission devices, for example, a clutch sleeve. This end output element is part of the end output mechanism, which apart from the clutch sleeve comprises a shifting fork, for example, that is connected with the clutch sleeve and can be moved with a shifting finger that can be actively connected with it, causing the clutch sleeve to be moved in order to engage or disengage a gear ratio step, wherein the shifting finger is part of the end actuating mechanism that actuates the end output mechanism. The end actuating mechanism, which can be triggered by an actuator and can include the kinematic transmission of the actuator movement onto an actuating element, such as a shifting finger, can comprise at least a main actuating element such as shifting fingers, which is actively connected with the end output mechanisms such as shifting forks and sliding sleeves in such a way that a gear ratio step can be engaged and that at least one main actuating element can be actively connected with another end output mechanism without having to disengage the previously engaged gear ratio step, wherein the end actuating mechanism can comprise at least one secondary actuating element, for example, at least one additional shifting cam. The end output mechanisms in accordance with the invention can comprise connecting elements such as shifting forks, which are equipped with a first functional area for engagement of a main actuating element and a second functional area for engagement of a secondary actuating element. The secondary actuating element can be arranged, for example, on a control shaft that articulates around its longitudinal axis upon actuation, wherein the second functional area can be designed so as to allow power to be transmittedxe2x80x94upon rotation of the control shaftxe2x80x94from one secondary actuating element onto the second functional area in the disengaging direction of the appropriate gear ratio step, with this power being equal to or larger than the force that is required for disengagement.
As soon as at least one main actuating element actively connects with an end output mechanism, at least one secondary actuating element can actively connect with at least one additional end output mechanism. For the purpose of disengaging the appropriate gear ratio steps, it can prove furthermore beneficial to actuate another end output mechanism through at least one secondary actuating element while actuating an end output mechanism for engaging a gear ratio step through at least one main actuating element. The end actuating mechanism can be designed so as to allow only one gear ratio step of a gear input shaft to be engaged at one time. Furthermore, secondary actuating elements and the functional areas in the end output mechanisms can interact in such a way that a gear ratio step is disengaged when rotating the control shaft regardless of the rotational direction, wherein an secondary actuating element and these functional areas are of symmetrical design. It is beneficial when at least one secondary actuating element has two cam-like end areas and the functional areas have corresponding recesses. Furthermore, the functional areas can be equipped with two cam-like end areas and at least one secondary actuating element can have corresponding recesses. Transmission of power between the secondary actuating element and the functional areas can occur, for example, through the tips of the cam-like end areas or through the side areas of the cam-like end areas. Further embodiments and a more detailed description with regard to function are revealed in the unpublished application DE 101 08 990.2, which hereby is included with its full content in the present application.
Based on the idea of the invention, the end actuating mechanism can also perform the synchronization of the gear input shaft through the synchronizing device on the last gear pair, for example, with the sliding sleeve actuating only the friction device of the synchronizing device of the last gear pair by performing an axial movement that corresponds to the engagement of the last gear ratio step, however not really actuating the shifting clutch, but rather moving it back into the starting position after decelerating the gear input shaft and the gear input shaft reaching the synchronizing speed. Of course, the friction device of the synchronizing device on the last gear pair is appropriately designed so as to perform the synchronization of the gear input shaft for all gear ratio shifts on the gear ratio steps that are arranged on this gear input shaft. This feature can include particularly resistant, wear-proof friction components such as ceramic friction disks or conventional friction lining with a large wear range. Furthermore, it can provide for easily exchangeable friction disks, e.g. fins that are open on one side and arranged in finned cages, which can be slid easily over the shaft around which the synchronizing device is arranged. The usage of the end actuating mechanism with at least one main and one secondary actuating element can be particularly beneficial in that the synchronizing device on the last gear pair is actuated through the secondary actuating element for the purpose of synchronizing the speed of the first gear input shaft to the speed of the gear output shaft during a gear ratio step switch and that the gear ratio step switch occurs through the main actuating element. This allows the deceleration of the gear input shaft through the secondary actuating element to occur nearly simultaneously and in the same operation as the disengagement of the engaged gear ratio step with the main element so that practically no loss of time occurs over the arrangement of separate synchronizing devices on each gear stepxe2x80x94an arrangement that requires considerably more space and is more cost intensivexe2x80x94and a simplified actuation of the synchronizing device over actuation through a separate or kinematically complicated end actuating mechanism that is dependent upon the end actuating mechanism for disengaging and engaging the remaining gear steps can be suggested. Of course, the secondary actuating element can also engage the last gear ratio step.
Based on an idea of the invention, the drive unit can still be formed by an internal combustion engine with a crankshaft, which can be connected with a gear input shaft through a double clutch. For this, an electric unitxe2x80x94as the one described above as first electric unitxe2x80x94can be connected additionally with at least one gear input shaft in such a manner that it can be uncoupled. It may be particularly beneficial to arrange the electric unit in such a way that it can be connected alternatively with both gear input shaft. This connection can be formed with a friction, shifting or magnetic clutch, which creates the connection of the electric unit with the gear input shaft by creating electromagnetic fields, wherein the formation of the connection and/or the selection of this clutch can occur through an actuator with electric, hydraulic and/or pneumatic as well as combined features or in the case of a magnetic clutch by the appropriate selection of electric currents by devices that adjust the magnetic effect, such as coils or similar. Of course, two clutches may also be advantageous for forming a connection between the gear input shafts and the electric unit that can be uncoupled, wherein one clutch respectively can connect the electric unit with one of the gear input shafts and for which two appropriate actuators can be employed.
At least one secondary unit can be connected with the electric unit from a drive point of view; it may be particularly beneficial if in the case of an arrangement of the electric unit parallel to the axis of the gear input shaft the electric unit is integrated into the pulley plane of the secondary unit. The electric unit can perform a drive function in the conventional sense, wherein the electric unit in a beneficial embodiment can be uncoupled from the gear input shaft so that the secondary units can be operated by the electric unit independently from the speeds of the gear input shaft, i.e. also independently from the speeds of the driving wheels and the speed of the drive shaft of the internal combustion engine. If it is desired to operate the secondary units electrically independently from the drive unit, this design is beneficial because it eliminates the separate supply of these secondary units with an electric unit and reduces the weight accordingly. Furthermore, a gear ratio may be provided between the electric unit and at least one secondary unit that can be adjusted variably, for example, through a variably adjustable belt wrap gearbox (CVT) or through gearwheel connections that can be actuated automatically or manually. It can also be beneficial to uncouple the electric unit from at least one secondary unit through a so-called secondary unit clutch. Several secondary units that are arranged in a pulley plane can be separated from, connected with and/or subjected to a gear ratio process with each other and/or the electric unit, also through clutches, free-wheels and appropriate gearboxes for selecting variable and/or fixed gear ratios.
Another beneficial embodiment may involve the usage of energy recovered during recuperation for supplying hydraulic accumulators when employing hydraulic devices, e.g. a hydraulic actuating device of at least one of the clutches, wherein, for example, the recuperation energy that has been converted into electric energy supplies an electric pump or wherein a pump that is coupled to the drive branch directly supplies the accumulator during a recuperating process by utilizing the kinetic energy that is provided by the driving wheels. The advantage of such methods and designs is that a usually occurring intermediate storage process, for example, in an electric accumulator, can be avoided, thus allowing the overall efficiency of the recuperating process and thus of the motor vehicle to increase. Of course, the direct operation of a secondary unit with kinetic energy offers the greatest efficiency and in particular applications, for example, when a secondary unit cannot be directly connected actively with the drive branch for spatial reasons, the energy created by the electric unit can be supplied directly and without intermediate storage in an accumulator to an electrically operated secondary unit, e.g. a pump for an actuating device of clutches, steering booster devices, chassis stabilization device and/or similar, a compressor for air conditioning devices, compression of the intake air for the internal combustion engine, compressed air brakes and/or similar, which can be arranged in accordance with the spatial conditions. Priorization of the power supply and/or energy supply with a combination of individual power users and/or energy consumers can be provided in dependence of the charge state of the electric accumulator during a recuperation process. The highest priority is beneficially assigned to the supply of safety-relevant users such as the steering booster pumps, the braking devices, the actuating devices for clutches, the chassis stabilizing components, engine controls and similar before users providing comfort such as air conditioning compressors, seat heating, window openers and similar; after that excess energy can be stored e.g. as electric energy in an electric accumulator or e.g. as thermodynamic energy in an air conditioning compressor, e.g. as carbon dioxide snow, as condensed supercritical gas or similar.
In the shifting device mentioned above in accordance with the invention, the end output element is the element that is moved in order to set the gear ratio, i.e. the one which establishes the connection between two power transmission devices, such as a clutch sleeve. This end output element is part of the end output mechanism, which apart from the clutch sleeve comprises e.g. a shifting fork, which is connected with the clutch sleeve and can be slid through a shifting finger that can actively interact with it, so that the clutch sleeve is moved in order to engage or disengage a gear ratio step, wherein the shifting finger is part of the end actuating mechanism that actuates the end output mechanism; the end actuating mechanism is the entire kinematic chain between the shifting and/or selecting drive and end output mechanism.
In state-of-the-art gearboxes, the end output mechanism and end actuating mechanism interact so as to allow a gear ratio step to only become engaged when no other gear ratio step has been engaged. In order to engage a gear ratio step, all other gear ratio steps must therefore be disengaged first. For example, control shaft openings, with which the shifting finger can be connected in order to shift the clutch sleeve through the respective control shaft, are designed in such a way that the shifting finger can only connect with another shifting fork if the clutch sleeve, with whose shifting fork it is connected at that time, has assumed a neutral position. With regard to a conventional manual transmission with an H-figure this means that a selection movement of the gear shift lever from one shifting channel into another can only occur in the neutral channel, wherein with a lever movement from one shifting channel into the neutral channel always the gear ratio step that was just engaged will be disengaged. The gear ratio steps, which can be engaged with the same clutch sleeve, cannot be engaged simultaneously anyhow. Therefore, it is necessary for a shifting process to disengage a previous gear ratio step, perform a selection movement and then engage a new gear ratio step; during this time, the flow of torque is interrupted by an engaged starting clutch since the branch must be free from load during the shifting process.
Particularly in the case of gearboxes that can be shifted with load, where the gear ratio steps form groups between which tractive force-uninterrupted load shifting can be performed, for example, by allowing the gear ratio steps to be wrapped by various parallel transmission branches that are allocated to different output elements of a friction clutch so that a continuous change of the torque from one branch to the next can be affected by actuating a friction clutch, designs of connections of the end output mechanism with the end actuating mechanism have been known that permit the engagement of one gear ratio step without having to disengage another gear ratio step that has possibly already been engaged. This way it is possible to engage several gear ratio steps simultaneously in several transmission branches through a single end actuating mechanism by first engaging a gear ratio step in one branch, with the shifting finger then connecting with other shifting forks in order to engage additional gear ratio steps without having to disengage the appropriate gear ratio step. In this connection, we would like to refer to application DE 100 20 821 A1 by the applicant, whose contents are also part of the disclosure content of the present application.
Generally, two groups of gear ratio steps are formed, wherein with regard to the graduation of their gear ratio subsequent gear ratio steps are part of different groups. For example, in the case of a gear box with one reverse gear (R) and six forward gears (I-VI) one group comprises gears I, III and V and the other group comprises gears R, II, IV and VI.
Such a gearbox offers the possibility of having engaged a gear ratio step in the transmission branch closed in the flow of torque through the friction clutch and to then engagexe2x80x94in another still open branchxe2x80x94the gear ratio step into which subsequently the switch is supposed to occur through diversion of the flow of torque onto the appropriate branch. During an acceleration process, for example, while the gear III has been engaged in a closed gear branch, the gear IV can be engaged in another branch. If however suddenly a shifting back into gear II should occur, the gear IV must first be disengaged and then the gear II be engaged, which represents a particularly high loss of time when the gears II and IV are shifted by different clutch sleeves.
It would also be feasible to have a situation where in the open transmission branch more than one gear ratio step is engaged, which represents a very large safety risk because as soon as this branch is integrated into the flow of torque several gear ratio steps with differing gear ratios become active, which can block or even destroy the transmission.
Additionally, so-called drum controller transmissions are known, where the end output mechanisms of the gear ratio steps are actuated through a rotating drum controller. In the drum controller, e.g. shifting gate-like grooves are incorporated, which extend on the surface of the cylindrical drum controller both in circumferential direction and in axial direction so that upon rotation of the drum controller around its longitudinal axis shifting forks, which are connected with the drum controller kinematically through elements traveling in the grooves, move in the axial direction of the drum controller; the shifting sequence of the gear ratio steps in relation to the rotation of the control shaft is set by the course of the grooves. With an appropriate design of the grooves, such drum controller transmissions allow the disengagement of an old and the engagement of a new gear ratio step to overlap, which offers a certain time advantage during the shifting process and thus reduces the duration of the tractive force interruption, however only sequential shifting is possible, e.g. shifting from gear I into gear III is just as impossible as a direct shifting back from e.g. gear V into gear I.
This task is resolved with the feature that in a gear boxxe2x80x94where the end actuating mechanism comprises at least one main actuating element such as shifting fingers that interacts, e.g. through axial displacement of a control shaft on which it is arranged, with the end output mechanisms, which are formed e.g. by shifting forks and clutch sleeves that are connected with them, in such a manner that a gear ratio step can be engaged, e.g. by rotating the control shaft on which at least one main actuating element is arranged, and that it can then connect with another end output mechanism without having to disengage the previously engaged gear ratio stepxe2x80x94the end actuating mechanism comprises at least one secondary actuating element.
In accordance with one particularly preferred embodiment at least one secondary actuating element interacts with at least one additional end output mechanism, e.g. in a certain position, a main actuating element interacts with a end output mechanism, while simultaneously secondary actuating elements interact with the additional end output mechanisms, as soon as at least one main actuating element interacts with the end output mechanism. Upon actuation of an end output mechanism for engaging a gear ratio step through at least one main actuating element, e.g. by rotating the control shaft, it is beneficial if at the same time at least one additional end output mechanism is actuated through at least one secondary actuating element for disengaging the appropriate gear ratio steps. It is particularly useful that this way only one gear ratio step can be engaged at one time and that due to the overlapping disengagement of the old and engagement of the new gear ratio step as well as the already performed selective movement a considerably time advantage is achieved.
Based on another, also particularly preferred embodiment for a gear box where the gear ratio steps form groups among which a tractive force-uninterrupted switch can occur, at least one secondary actuating element interacts with at least one additional end output mechanism of the same group as soon as at least one main actuating element interacts with an end output mechanism of a group. In this embodiment, it is very useful that upon actuation of a end output mechanism of one group for engaging a gear ratio step through at least one main actuating element at the same time at least one additional end output mechanism of the same group is actuated through at least one secondary actuating element for disengaging the appropriate gear ratio steps. It is beneficial if at least one secondary actuating element interacts with no end output mechanism of the other group as soon as at least one main actuating element interacts with a end output mechanism of one group. It is very useful that this way a gear ratio step can be engaged simultaneously in each group, but not several gear ratio steps of one group.
Based on an exemplary, but particularly preferred embodiment of the end output mechanisms, which comprise connecting elements such as shifting forks, they are equipped with a first functional area for engaging a main actuating element and a second functional area for engaging an secondary actuating element so that each end output mechanism can be actuated through a main actuating element or through an secondary actuating element. On a gear box at least one secondary actuating element is here arranged on the control shaft that can rotate around its longitudinal axis upon actuation and the second functional area is designed in such a way that upon a rotation of the control shaft a force can be transmitted from one secondary actuating element to the second functional area in the disengagement direction of the appropriate gear ratio step, with this force being equal to or larger than the force that is required for disengagement. The connection between the secondary actuating element and end output mechanism must not be suited to also transfer a force for engaging a gear ratio step.
In another embodiment a design of at least one secondary actuating element is preferred that makes it possible to connect the secondary actuating element with at least two end output mechanisms. For this, at least one secondary actuating element is particularly wide in the control shaft axial direction, which preferably corresponds at least roughly to the width of two shifting fork mouths and their joint distance.
Based on a particularly preferred embodiment, at least one secondary actuating element and the second functional areas interact so as to disengage a gear ratio step upon rotation of the control shaft independently from the rotational direction. Starting from the original position in which the control shaft is in a mean position in relation to its rotation and in which also the main actuating element has become engaged with the first functional area of a end output mechanism, a gear ratio step is engaged by rotating the control shaft either to the right or the left, wherein in any case at least one secondary actuating element actuates the gear ratio step(s) that is (are) are assigned to it with regard to disengagement.
In the embodiment it is considered particularly beneficial if for this purpose at least one secondary actuating element and the second functional areas are of symmetrical design.
In a particularly preferred example, at least one secondary actuating element is equipped with two cam-like end areas and the second functional areas with corresponding recesses.
In another, also particularly preferred embodiment, the second functional areas are equipped with two cam-like end areas and at least one secondary actuating element with corresponding recesses.
Transmission of power between the secondary actuating element and the second functional area occurs through the tips of the cam-like end areas, wherein in another embodiment it is also useful if the transmission of power between the secondary actuating element and the second functional area occurs through the side areas of the cam-like end areas.
In order to resolve the task, these beneficial embodiments are based on an inventive method that contains at least the following procedural steps:
the drive unit drives at least one of the gear input shafts at least some of the time;
the first electric unit drives one of the gear input shafts at least some of the time;
the first electric unit is driven by one of the gear input shafts at least some of the time.
The invented method can at least provide for a starting of the drive unit, which has the design of an internal combustion engine, wherein in the case of a cold internal combustion engine this unit is started preferably through a method that uses the idea of the invention in connection with beneficial arrangements of the drive branch that include one clutch, respectively, between the internal combustion engine and gear input shaft and contain the following procedural steps:
both clutches are engaged;
no gear has been engaged between the first gear input shaft, with which the first electric unit is connected from a drive point of view, and the gear output shaft;
a gear with preferably a small gear ratio (multiplication or reduction) has been engaged between the second gear input shaft and the gear output shaft;
the first electric unit is driving the first gear input shaft;
the clutch in the power distribution flow between the first gear input shaft and the drive shaft is disengaged after reaching the torque that is required for a cold start of the electric unit;
after starting the drive unit the clutch in the power distribution flow between the drive shaft and the second gear input shaft is disengaged and the vehicle starts to run.
This method can alternatively or additionally be combined with another method for starting the internal combustion engine, wherein this method is preferably employed for a drive unit in the warmed-up state and contains the following procedural steps:
no gear has been engaged between the first gear input shaft, with which the first electric unit is connected from a drive point of view, and the gear output shaft;
a gear with preferably a small gear ratio (multiplication or reduction) has been engaged between the second gear input shaft and the gear output shaft;
the clutch in the power distribution flow between the first gear input shaft and the drive shaft is disengaged;
the first electric unit is being driven and the drive unit is started;
by disengaging the clutch in the power distribution flow between the drive shaft and the second gear input shaft the vehicle starts to run.
Alternatively or additionally, the following starting procedure can prove beneficial, particularly for a cold internal combustion engine in connection with the arrangement of a fixed wheel on the first gear input shaft and an idler with a shifting sleeve, a so-called triplex sleeve, that interacts with the fixed wheel, with the sleeve being arranged on the gear output shaft and being able to connect selectively the gears of a gear pair with each other, to connect one of the gears positively with the gear output shaft or to assume a neutral position without connecting function:
no gear is engaged between the first gear input shaft, which is connected with the first electric unit from a drive point of view, and the gear output shaft;
the two gears are connected with each other through the triplex sleeve between the second gear input shaft and the gear output shaft;
the clutch in the power distribution flow between the second gear input shaft and the drive shaft is disengaged;
the electric unit is being driven and the drive unit is being started;
the clutch between the drive unit and second gear input shaft is being engaged;
the second gear input shaft and the gear output shaft are decelerated to a negligible speed, for example, through the electric unit;
the triplex sleeve is moved into the neutral position;
a gear with a small gear ratio between the second gear input shaft and gear output shaft is engaged;
by disengaging the clutch in the power distribution flow between the drive shaft and the second gear input shaft the vehicle starts to move.
A large advantage of this method is a cold start of the internal combustion engine at high speedxe2x80x94caused by the gear ratio steps of two gears, for example, the second and the fifth gearxe2x80x94and thus a reduced torque of the electric unit. In connection with an appropriate transmission design, the elimination of a pulse start with a cold internal combustion engine is made possible, also and particularly for temperatures under the freezing point, and the electric unit can become more cost effective and have smaller torques. This can lead to enormous cost and space savings.
The invented method can additionally comprise the following procedural steps for operating the first electric unit as a generator for creating electric energy:
the first electric unit is driven by the drive unit or for a driving mode such as recuperation by at least one driving wheel;
when driven by the drive unit selectively one of the two clutches in the power distribution flow between the drive shaft and one gear input shaft is disengaged;
when driven by at least one driving wheel both clutches are engaged, wherein it may be beneficial to operate the electric unit in dependence on the charge state of electric energy accumulators, such as a high current battery, a power capacitor and/or similar, i.e. to connect it with the gear input shaft, which thus transmits a torque, which is transmitted from the wheels and/or from the drive unit to the shaft, to the electric unit.
For the method in accordance with the invention, the following torque flows can be beneficial:
torque is transmitted from the drive shaft of the drive unit through the disengaged clutch in the power distribution flow between the first gear input shaft, which holds, i.e. is actively connected with, the electric unit, and the drive shaft to the first gear input shaft and from there to the rotor shaft of the electric unit;
torque is transmitted from the drive shaft of the drive unit through the disengaged clutch in the power distribution flow between the second gear input shaft without electric unit through a pair of gears to the gear output shaft, from there through a pair of gears to the first gear input shaft and from there to the rotor shaft of the electric unit;
torque is transmitted from at least one driving wheel to the gear output shaft and from there through a pair of gears via the first gear input shaft to the rotor shaft of the first electric unit. The first electric unit can be operated at a speed, preferably by selecting an appropriate gear wheel pair between the gear output shaft and the first gear input shaft, where it reaches its optimal operating point with regard to efficiency. It may be beneficial to uncouple the drive unit from the first gear input shaft during the recuperating process with a switch from xe2x80x9cpullxe2x80x9d to xe2x80x9cpushxe2x80x9d by engaging the clutch between the first gear input shaft and the drive shaft in a delayed fashion, e.g. with a delay of  greater than 0.3 seconds after the switch from xe2x80x9cpullxe2x80x9d to xe2x80x9cpush.xe2x80x9d
The recuperating process can be performed particularly beneficially in connection with a gear box with an electric unit that can be connected between the gear input shafts because a switch of the electric unit to the appropriate gear input shaft and selection of the most favorable gear for the recuperating process allows efficiency to be improved further since all gears of the transmission can be used for adjusting the speed with the highest efficiency of the electric unit. Based on another inventive idea, recuperating energy can be stored through additional energy storage types, e.g. thermal energy, pressure and similar, particularly in the case of an already charged electric energy accumulator. For this, energy conversion units such as compressors, Peltier elements, Piezo elements and similar that are attached to the rotor shaft can be used. The secondary units, which were used, for example, as air conditioning compressors above, can also be provided for this.
Another beneficial variation of the invented method can include a feature that the first electric unit additionally or alternatively to the drive unit, which can be a second electric unit or an internal combustion engine, transmits torque to the first gear input shaft for driving the motor vehicle and from there through a gear pair between the first gear input shaft and gear output shaft to at least one driving wheel. The pair of gears can either be selected based on the driving situation or the gear pair of the currently engaged gear can be used.
The method in accordance with the invention furthermore provides a feature that the first gear input shaft with the first electric unit is decelerated during shifting processes for the synchronization of the gears and thus the moment of inertia of the rotor of the electric unit is reduced so that the synchronizing devices are not overloaded and possibly can even eliminated, wherein the deceleration of the first gear input shaft can occur by briefly closing the clutch between the drive unit and the first gear input shaft, while the flow of torque between the drive unit and the driving wheels takes place through the second gear input shaft. The extent of deceleration of the gear input shaft depends on the synchronizing speed of the first gear input shaft that must be set. Monitoring of the synchronizing speeds can occur through appropriate speed sensors that are attached to the gear input shaft such as a sensor that is already incorporated in the electric unit for controlling it and/or on the gear output shaft and/or on the driving wheels as wheel speed sensors, wherein when fastening them to the gear output shaft they are accordingly calculated while taking the gear ratios of the engaged gear between both shafts into consideration. Furthermore a feature may be included where with non time critical upshifting processes, i.e. during shifting processes that occur toward overdrive with regard to their gear ratio, electric synchronizing procedures take place exclusively, while in the case of down-shifting processes exclusively mechanical synchronizing procedures take place. This method includes among other things the advantage that the expenditure of electric energy is minimized during down-shifting processes and that electric energy can be gained when upshifting due to a delay of the gear input shaft. Acceleration of the gear input shaft to the synchronizing speed when down-shifting can occur, for example, by briefly closing the appropriate clutch. Of course, synchronization can occur both mechanically and electrically in the case of time critical shifting processes.
The shifting sequence from a gear with lower gear ratio to a gear with higher gear ratio for a transmission with an appropriate method takes place by engaging, for example, the gear with low gear ratio between the first gear input shaft and the gear output shaft, closing the clutch between the drive unit and first input shaft and thus transmitting torque from the drive unit through the clutch to the gear input shaft, from there through the gear pair to the gear output shaft and from there to the driving wheel. During this time, the next gear is engaged on the second gear input shaft with an engage clutch between the drive unit and second gear input shaft, wherein synchronization of the second gear input shaft can be supported by a slipping contact of the clutch between the drive unit and second gear input shaft orxe2x80x94if the second electric unit is arranged on this gear input shaftxe2x80x94by accelerating or decelerating the electric unit. Of course, upshifting into the next gear can occur in the same fashion, i.e. by first transmitting torque to the driving wheel through the second gear input shaft, while engaging the next gear on the first gear input shaft, and then closing the clutch to the first gear input shaft and engaging the clutch to the second gear input shaft. The shifting sequence from a gear with higher gear ratio to a new gear with lower gear ratio takes place in a similar fashion, i.e. by engaging and synchronizing the next lower gear on the gear input shaft that is not connected with the drive unit through the clutch, with then the clutch interrupting the flow of torque through the engaged gear and starting the new gear by closing the clutch to the gear input shaft with the new gear.
Another beneficial shifting variation can include the shifting from a gear with higher gear ratio to a gear with lower gear ratio on one and the same gear input shaft, i.e. a downshift on the same gear input shaft, which can be performed beneficially with the following procedural steps:
adjustment of the drive unit to increased power, preferably full load;
slipping operation of the clutch in power distribution flow between a gear input shaft on which the gears that are to be shifted are to be arranged and the drive shaft;
upon reaching the synchronizing speed for a gear that is between the gears on the one gear input shaft with regard to its gear ratio on the clutch between the drive shaft and the other gear input shaft, this clutch is operated in a slipping manner and torque with regard to its gear ratio between the gears on the gear on the one gear input shaft is directed to at least one driving wheel through the gear output shaft;
the clutch between the drive shaft and the one gear input shaft is disengaged;
upon reaching the synchronizing speed of the new gear that is to be engaged on the one gear input shaft the shifting process to this gear takes place.
It may prove beneficial when shifting from one gear to a new gear with lower gear ratio on the same gear input shaft that is to be engaged to additionally use the electric unit during the synchronizing process to the new gear that is to be engaged if the electric unit is actively connected with this gear input shaft. For the synchronization of at least one new gear that is to be engaged, which preferably is the gear with the smallest gear ratio on the gear input shaft with which the electric unit is connected from a drive point of view it may furthermore be beneficial to employ the electric unit for decelerating the gear input shaft that is connected with it while accelerating the motor vehicle through the gear input shaft without electric unit. The gear input shaft is preferably decelerated basically to the synchronizing speed of the new gear that is to be engaged.
Based on the inventive idea, another beneficial method that can be applied for arrangements of gear boxes allows an electric unit to be connected with a gear input shaft through a shifting clutch, which at the same time can connect the gear with the largest gear ratio with the gear output shaft. This shifting clutch undergoes the following shifting modes:
the idler of the gear pair of the gear is arranged on the gear input shaft in an articulating manner, the electric unit is uncoupled from the gear input shaft;
the electric unit is uncoupled from the gear input shaft;
the electric unit is coupled to the gear input shaft, the idler can be rotated in relation to the gear input shaft;
the idler is connected with the gear input shaft in a stationary manner, the electric unit is coupled with the gear input shaft;
the electric unit is connected with the idler, the idler can be rotated in relation to the gear input shaft.
Based on the idea of the invention, the method furthermore sees beneficial steps for the sole operation of the motor vehicle with the first electric unit or its operation that supports the internal combustion engine and/or a second electric unit in its place. The clutches between the drive shaft and the gear input shafts can be opened, and in accordance with the driving situation a selected gear pair that is connected between the gear input shaft and the gear output shaft can transmit torque from the electric unit to at least one driving wheel. Additionally the method can provide for support by the first electric unit to the drive unit for operating the motor vehicle so as to allow the first electric unit to directly interact with the gear input shaft in a power distribution flow from the drive shaft to the gear output shaft through the gear input shaft, which can be coupled with the first electric unit, to engage the clutch between the drive shaft and the gear input shaft with the electric unit with a power distribution flow through the gear input shaft without electric unit, and to transmit the torque fed by the electric unit to the gear output shaft through a gear pair that has been selected in dependence of the driving situation. Furthermore, in the case of a gear box arrangement with an electric unit that can be shifted between the gear input shafts, it may be particularly beneficial to connect the electric unit of the gear input shaft that does not transmit any torques from the crankshaft to the gear output shaft at that time and to operate it through one of the gears that are arranged on this gear input shaft at a gear ratio that is optimal for efficiency.
Based on another idea of the invention, a creeping movement of a vehicle with the invented double clutch gear, i.e. a slow forward motion of the motor vehicle from the stopped position such as during congested or stop-and-go traffic areas or similar traffic situation, may be beneficial. The starting situation can be a vehicle with a selected driving mode with engaged gear and put-on brakes, wherein the internal combustion engine is not in operation. In accordance with the idea of the invention, a differentiation can now be made as to whether the motor vehicle is supposed to be operated in the creeping mode or quickly accelerated. The starting process for the internal combustion engine can be initiated either in dependence on the releasing of the brakes and/or by indicating a driving request, e.g. by signaling a load requirement to the internal combustion engine such as the actuation of the accelerator pedal such as the gas pedal. Compared to the exclusive evaluation of the accelerator pedal such as the gas pedal this can save time, and the internal combustion engine can be started sooner. Additionally, a creeping movement of the vehicle can be excluded and it can be accelerated immediately when releasing the brakes quickly and actuating the gas pedal quickly, while during a slow release of the brake pedal a creeping process can be initiated. Depending on the behavior of the driver, a differentiation can be made among the following incidents with the respective subsequent procedural steps:
a) release the brake pedal, no actuation of the gas pedal after a stop phase:
the available torque of the electric unit is transmitted through the clutch between the gear input shaft with the electric unit and the crankshaft;
between the other gear input shaft and the gear output shaft, torque that is sufficient for a creeping movement of the vehicle is transmitted to the gear output shaft simultaneously through a gear with a low gear ratio, i.e. the gear with the lowest gear ratio, in the case of a slipping clutch between this gear input shaft and the crankshaft;
after starting the internal combustion engine, the internal combustion engine provides the creeping moment and the electric unit is switched off.
The transmitted torque on the clutch between the gear input shaft without electric unit and the crankshaft may be reduced down to zero if necessary in order to achieve a faster start of the internal combustion engine.
b) the driver actuates the accelerator pedal;
with released brakes and engaged clutch between the gear input shaft with the electric unit and with an engaged low gear between this gear input shaft and the gear output shaft, the creeping moment is generated through the electric unit and directed to the driving wheels;
upon actuation of the gas pedal the engaged gear is deactivated;
the clutch between the crankshaft and gear input shaft with electric unit is disengaged;
a gear with low gear ratio between the gear input shaft without electric unit and gear output shaft is engaged;
the internal combustion engine is started through the electric unit;
the clutch between the crankshaft and gear input shaft with the electric unit is opened after the start, the other clutch is disengaged and the vehicle starts to move.
Of course, in accordance with the statements provided under a), here as well the clutch that needs to be disengaged after the start can be adjusted to a defined creeping moment.
Advantageously, the clutch between the gear input shaft with electric unit and the crankshaft is before the tactile point in order to shorten its engagement time.
Further beneficial embodiments, in particular for increasing shifting comfort and dynamics, e.g. for double and/or triple upshifting and/or down-shifting without a drop in tractive force, can include the integration of additional and/or the separation of existing gear input shafts or secondary shafts with additional gear pairs.
Another advantageous shifting sequence is provided by the idea of the invention in such a way that during a shifting process between a first gear, e.g. the gear II on a first gear input shaft, and a second gear with a higher gear ratio than the first gear, e.g. the gear III on a second gear input shaft, the clutch between the crankshaft and the first gear input shaft transmits torque to the electric unit that is actively connected with the clutch until the crankshaft has achieved roughly the speed that is required for a jerk-free operation of the second gear. This way, disadvantageous speed adjustments of the internal combustion engine can be foregone, for example, by reducing the load of the internal combustion engine by adjusting the firing anglexe2x80x94connected with a shortened life of the catalytic converter due to an increased concentration of unburnt hydrocarbon. The advantage of the electric unit over this method consists particularly of its clearly improved controllability and high dynamics so that the acceleration gradients to the drive shaft can be kept low and an increased feeling of comfort arises when shifting. Furthermore the energy supply to the clutches can be reduced, which leads to an increased life and lower fuel consumption.